Ash can be alkaline and care is needed if your addition is to a neutral or alkaline soil as it may engender micronutrient deficiency.

If you have straw and manures these can be added to composts using staw as a bed and cover and manure as a layer with the ash some soil clay and rock phosphate and gypsum.

The compost stabilizes the carbon by the organo mineral complex which is facilitated by the Calcium working as a mortar. The naked organic matter is soil is of short longevity while the organo mineral complex can endure for long periods of time. Ashes of rice will provide Silicon which is very favorable to adaptive reactions in relations to drought and pests.

Better to go foe mulching or making compost out of rice or vegetable crop residue rather than burning and adding that ash.

Dear Mahin,

i am attached here some papers which is useful for your research work.

All the best

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.303.978&rep=rep1&type=pdf

http://www.journal.au.edu/au_techno/2008/apr08/journal114_article08.pdf

http://link.springer.com/article/10.1007/BF00881147#page-1

 Good discussion on rice husk affect on soil stabilization.The purpose of the question is not clear.If it is for improving soil conditions for agricultural purpose then composting of husk may be a better route.If rice husk ash is available from some source that can be used on agricultural soils.Ash contains 60-70 percent silica and rest basic cations and anions .Divalent cations of Ca,Mg and Fe and anions of phosphate,chloride and sulphate may be present.The silica can be a beneficial plant nutrient especially in rice and sugar cane crops.So the ash can be recycled in rice  and sugarcane cultivation.Ca silicate can be a binding agent (other cations can also).References provided by colleagues suggest that the ash can stabilize or moderate swelling and shrinking properties of black soils for construction purpose.It can also improve the properties of cement used in construction.I understand that the beneficial  role of rice husk ash is due to silica and the dominant divalent cations in the ash.As pointed out by Dr.Hepperly that this ash when added manure or compost heap/pit it will improve the stability of manure and in turn the stability of soil when manure is applied to soil.

It depends on the  burning level alps, is it partly burnt or fully burnt, the composition of the resultant ash is different. If you want to add to soil as an amendment  need to have an idea of the carbon content. If you need o incorporate to soil you have to add some nitrogen and get the C:N ratio near to the soil range as 10:1, if the carbon is high you can use it as a mulching material on the soil. The ash also provide many minerals as potassium, but if you want to get the maximum benefit of the plant residues why don't you go for as composting process and save all the nutrients in the bio-mass

Partly burned Rice Husk, as it comes out from the burners of the Rice Mills (where husk is used as a fuel) is a good biochar! In our practice, this may be utilized for composting of all kinds of animal and fecal waste - just mix the waste in the husk biochar (this is a unique biochar as it is uniformly powdered)  and then is covered at the top by two inches with the same. Since this is uniformly highly aerated medium, the system offers easy aerobic degradation and the nutrients will be easily adsorbed to the charcoal - within 3-6 months a very good organic fertilizer will be ready! Try and practice!

Dear,

Rice ash is a very good source for the minerals such as silica which is in very high amount in the rice husk ash. It can be used as source of silica and potash for the rice cultivation and you can save lot of money which you spent on application of these two important minerals to the rice soil. Its application will also increase the water holding capacity of the soil and thereby increase the water productivity.